Silicon-containing polymer preparation



Patented Dec. 5, 1950 SILICON-CONTAINING POLYMER PREPARATION Leo WalterTyran, Niagara Falls, N. Y., assignor to E. I. du Pont de Nemours &Company, Wilmington, Del., a corporation of Delaware No Drawing.

Application July 24, 1945,

Serial No. 606,875

2 Claims. 1

This invention relates to polymer preparation, and more particularly, itrelates to the production of polymers obtained by the polymerization ofpolymerizable unsaturated alkyl silicon halides, unsaturated alkylsiliconic esters or a mixture of such halides or esters with apolymerizable nonsilicon-containing vinyl compound.

Silicone resins have become important industrial materials ,filling aneed for polymers of high temperature stability. These resins containmolecules based upon a structural backbone of silicon and oxygen ratherthan upon the carbon atoms of the conventional vinyl and butadiene typeof polymer. stances that provides high temperature stability, and thesame factor is responsible for the low solubility of these polymers incommon solvents. It has long been desired to have polymers which willcombine the high heat stability of the abovementioned silicone resinswith a comparatively high solubility in common solvents. It has alsobeen desired to obtain polymers which will have a relatively high heatstability combined with the high tensile characteristics and rubberyproperties of ordinary polymers based on carbon chain structures.

It is an object of this invention to produce polymer products having ahighenheat stability than carbon chain vinyl polymers, a highersolubility in common organic solvents than silicone resins, and a highertensile strength and rubbery character than silicone resins.

It is another object of this invention to produce polymers havingseveral of the desirable properties of silicone resins and carbon chainvinyl resins without some of the undesirable properties of thesematerials;

Other objects of the invention will appear hereinafter.

These objects may be accomplished, in general,

by polymerizing unsaturated alkyl silicon halides,

unsaturated alkyl siliconic esters, or such estersor halides mixed withpolymerizable carbon chain vinyl compounds.

It has now been discovered that unsaturated alkyl silicon halides andunsaturated alkyl siliconic esters, with or without polymerizable carbonchain vinyl compounds, can be polymerized by heating the same to atemperature between 50 C. and the boiling point thereof in the presenceof-a polymerization catalyst. Preferably the polymerizable substance orsubstances are heated while excluding air therefrom, for example, underrefluxing conditions or under an atmosphere of nitrogen. It is alsopreferred to heat the mate- It is the silicon content of these subrialsfor a period of at least twelve hours to obtain a suitable yield of thepolymer. The resulting polymer may be isolated in any desired manner,for example by evaporating to dryness the liquid left in the polymer.

Unsaturated alkyl halides and unsaturated alkyl siliconic. esters,employed in accordance with this invention, for the production of newpolymers and copolymers, are generally known compounds. These compoundsmay be generally represented by the formula:

in which R is an unsaturated alkyl group, R1 is a halogen or an alkoxyconstituent and R2 and R3 are halogen or a monovalent organic radical,i. e.. alkyl; aryl, alkaryl, aralkyl, alkoxy, aroxyalkyl, alkoxyaryl,etc. As examples of unsaturated alkyl halides and siliconic esters, thefollowing are representative Monovinyl silicon trihalide Divinyl silicondihalide Trivinyl silicon monohalide Allyl silicon halides Diallylsilicon dichloride x v Monovinyl, monoallyl silicon dihalide Monovinyl,monomethyl silicon dihalide Monovinyl trimethoxy silane Monoallyltrimethoxy silane Monoallyl triethoxy silane Monovinyl triphenyl silaneMonobutaclienyl silicon trihalide Monocrotyl silicon trihalide Diallylsilicon dichloride, (CH2=CHCH2)2SiC12, and method for producing same isdisclosed in Hanford patent application Serial No. 339,178, filed June6, 1940, now Patent No. 2,386,793, and monoallyl triethoxy silane,

CH2=CHCHzSi OC2H5) 3 is disclosed in an article by Andrianov andKamenskaya in J. Gen. Chem. (U. S. S. R.) 8 969 (1938). Chem.Abstracts33 1266 (1939). Monovinyl silicon trihalide, B. P. 86 C.-88 C. at 750mm. Hg, may be prepared by passing a vinyl halide, for example, vinylchloride over or through finely divided elemental silicon at atemperature of 375 C. to 500 C. Other unsaturated alkyl silicon halidesfor use in accordance with this invention, for example, divinyl silicondihalide, trivinyl silicon monohalide may be similarly prepared. Forexample, organo silicon halides containing isopropenyl. crotyl,difiuorovinyl, butadienyl, or other polymerizable radicals may beprepared from their halides in the manner above described. Vinylsiliconic esters may be prepared by esterification from thecorresponding vinyl Silicon halide. The halide may be, for example,reacted with alcohol in a reaction medium such as benzene.

One, two or three unsaturated alkyl radicals may be present in eachmolecule of the cream silicon halide. If a straight chain polymer ofgoodsolubility characteristics is desired, it is preferred that asilicon halide containing only one unsaturated alkyl radical permolecule be employed. If, on the other hand, it is desired to produce arelatively insoluble form-stable polymer, or copolymer, an organosilicon halide containing two or three unsaturated alkyl radicals permolecule is preferably used.

Any catalyst, organic or inorganic, commonly used to catalyze thepolymerization of unsaturated organic polymerizable monomers such asvinyl or acrylic organic polymerizable monomers, may-be employed tocatalyze the above-mentioned polymerization reaction. As examples ofsuch catalysts, the following may be named: peroxygen compounds, suchas, hydrogen peroxide, benzoyl peroxide, sodium peroxide, ammoniumpersulfate, potassium permanganate, acetic peracid, monoperphthalicacid, monoper succinic acid, perpropionic acid, and monopermaleic acid;ultraviolet light, ozone, aluminum chloride, boron trifiuoride and thelike. The quantity of catalyst used to catalyze the polymerizationreaction of the present invention may vary between wide limits. A traceof the catalyst is sufiicient to induce polymerization to take place andquantities up to or more are not harmful anddo not interfere with thereaction. However, more than 4% by weight of the catalyst used willusually fail to produce materially improved results. Preferably between0.05% and 3% of the catalyst is used in carrying out th polymerizationreaction.

The polymerization or copolymerization in accordance with this inventionmay be carried out in aqueous emulsion, in bulk, or in solution, or inthe case of unsaturated alkyl siliconic esters which hydrolyze slowly,it may be carried out in granular suspension. As above indicated, thepresent invention includes not 'only the polymerization of unsaturatedalkyl halides and unsaturated alkyl siliconic esters Or mixtures ofthem, but also includes the polymerization of mixtures of said halidesand esters with polymerizable, carbon-chain, non-silicon-containingvinyl monomer, for example, vinyl acetate, vinyl chloride, vinylcyanide, methyl methacrylate, and the like, to yield copolymers.

The polymerization products of the present invention. may, if desired,be treated with substances to change the character thereof, for example,with water to produce silicol polymers which may be condensed to yieldnon-thermo- 4 to be considered limitatlve of the scope or the invention.

Example I 0.005 to 0.01 gram of benzoyl peroxide were added to 4 gramsof diallyl silicon dichloride, (CH2=CHCH2)2SlC12, B. P. 162-163" C. andthe resulting mixture heated to a temperature of 70 C. while passingnitrogen therethrough for a period of 64 hours. The product was thenevaporated at a temperature of 120-130 C. to dryness leaving a residueof a polymeric allyl silicon chloride having a brown, transparentbrittle resinous character.

Example II Example III To a solution of 18.1 g. of diallyl silicondichloride dissolved in 100 ml. of benzene was added 6.4 g. methanol.The mixture was heated for half an hour at incipient boiling to removethe hydrogen chloride evolved. On cooling, the solu-' tion of methylsiliconic ester was treated with calcium carbonate for several minutesto remove-traces of acid. To the filtered liquid was then added 0.20 g.benzoyl peroxide. The solution was heated at reflux for 64 hours. Themixture was then evaporated to dryness with strong heating (120-130" C.)in a current of dry air for several hours. The residue was a shiny, tanbrittle resin and analysis indicated it to be a polymerized ally] methylsiliconic ester.

Example IV To a solution of 8.1 g. of monovinyl silicon trichloride in50 ml. benzene was added 4.8 g. methanol. The mixture was heated forhalf an hour at incipient boiling to remove the hydrogen chlorideevolved. On cooling, the solution of methyl siliconic ester was treatedwith calcium carbonate for several minutes to remove traces of acid. Tothe filtered liquid was then added 0.10 g. benzoyl peroxide. Thesolution was heated at reflux for 64 hours. The mixture was thenevaporated to dryness with strong heating (120130 C.) in a. current ofdry air for several plastic resins containing silicon-oxygen strucingout the present invention, it being understood that the details oitheexamples arenot hours. The residue was found to comprise a polymer ofvinyl silicontrimethoxide, a brownto-black brittle resin.

Example V hour at incipient boiling to remove the hydrogen chlorideevolved. On cooling, the solution of methyl siliconic ester is treatedwith sufficient calcium carbonate to remove traces of acid. The solutionis filtered and 0.2 gram benzoyl peroxide and 50 grams vinyl acetateadded thereto. The solution is then heated to a temperature of 70. C.while nitrogen is passed therethrough for a period of 64 hours. Themixture tions may be found, for example,

is then evaporated to dryness at a temperature of 120-130 C. The residueis composed of a copolymer of vinyl silicon halide and vinyl acetube andhas a tough resinous character.

Depending -upon the particular unsaturated alkyl silicon compoundemployed, on the temperature of polymerization; and on the presence orabsence of other polymerizable ingredients, various properties may beobtained in the polymeric products. The color may vary from white tobrown or black and the resins may have considerable variation inhardness and strength, ranging from hard, brittle resins to flexible,tough and only moderately hard resins. In general, the products of thisinvention are characterized by high softening point temperatures andinsolubility in water. The polymers and copolymers obtained inaccordance with this invention are soluble in benzene and other commonorganic solvents.

The silicon-containing polymers and copolymers of this invention havemany uses suggested by their high temperature stability. Applicaaselectrical insulation material, fabrication of motor gaskets and thelike. In view of the solubility of the polymers of this invention incommon organic solvents they may largely be used in the production offilms, tubes, coatings, filamentsand moldings.

Throughout the specification and claims reference to silicon halides is,of course, meant to includ bromides, iodides and fluorides although thechlorides, in view of their cheapness are greatly to be preferred.Reference in the speciflcation and claims to parts, proportions andpercentages, unless otherwise specified refers to parts, proportions andpercentages by weight.

Since it is obvious that manychanges and modifications can be made inthe above .decribed details without departing from the nature and spiritof the REFERENCES CITED The following references are of record in thefile of this patent:

UNITED STATES PATENTS Number Name Date 2,377,689 Hyde June 5, 19452,386,793 Hanford Oct. 16, 1945 2,394,642 Strain Feb. 12, 1946 2,396,692Garner Mar. 19, 1946 2,420,912 Hurd May 20, 1947 2,426,121 Rust Aug. 19,1947 2,436,304 Johannson Feb. 17, 1948 2,443,740 Kropa June 22, 1948OTHER REFERENCES Carothers, Collected Papers, Interscience, 1940, pp.85, 115, 119.

Hurd: Journal Amer. Chem. Soc, Oct, 1945, vol. 67. pages 1813 and 1814.

Andrianov: J. Gen. Chem. U. S. S. R., vol. 8,

. No. 10, pages 969-971, 1938. Translation -available in Div. is vol. 4of Organosilicon Literature by Dow-Corning Corp.

Fieser et 9.1.: Organic'Chemistry, Heath, 1944, page 154.

2. A RESINOUS HOMOPOLYMER OF VINYL SILICON TRICHLORIDE.